MIÓ, Sonesu Yeast Fermentation

Coffee cherries that begin drying while still attached to the tree are considered overripe and typically make up only a small percentage of the harvest. Last season was particularly challenging for farmers in Minas Gerais, as drought conditions accelerated cherry ripening. What would normally be a two-month harvest was compressed into a dramatically shorter timeframe. This surge in volume created significant logistical challenges at the processing station, and the abundance of overripe cherries could have been a serious quality issue, if not for some innovative thinking and experimental processing, spearheaded by Professor Lucas Louzada. The protocols which were developed have been used again this season with incredible results and offer some security as the environmental conditions become more unpredictable.

This yeast fermentation was conducted with around 51% overripe cherries. The fruits were fermented in closed tanks for 72h using Saccharomyces cerevisiae as a starter yeast. The result is a profile with bright, fruity acidity, high sweetness, and a silky body.

Mió is a forward-thinking, technology-driven coffee farm spanning 1,589 hectares. A third of the land houses coffee processing and milling facilities, alongside pasture areas and Eucalyptus trees, which are home to some thriving bee colonies. The remaining land is split evenly between coffee trees and a native forest reserve, which helps preserve the area's natural ecosystem. The estate's abundant spring water supplies many neighbouring properties, making one of Mió's core responsibilities not only to maintain the flow, but to also improve the water quality.

Through state-of-the-art facilities, Mió maintains exceptional traceability of their entire annual crop. Using satellite imagery, they monitor every stage of production—from cherry harvesting locations to truck movements and processing details. This advanced technology not only provides precise tracking but also improves farmworkers' quality of life, ensures bountiful harvests, and maintains the highest processing standards.

Mundo Novo is a coffee variety resulting from a natural cross between Bourbon and Typica, discovered in Mineiros do Tietê, São Paulo, Brazil. It's known for its productivity and good cup quality, but it's susceptible to major diseases. Mundo Novo has commercial importance in Brazil and other South American countries, including Peru. Costa Rica introduced it in 1952, but farmers didn't widely adopt it due to its very tall stature. This variety can also be found in Malawi, Africa. While vigorous and productive for a traditional American variety, Mundo Novo matures late.

Often called anaerobic fermentation, "anoxic" is the correct term for the environment where fermentation occurs. While fermentation itself is inherently anaerobic (not requiring oxygen), many other microbial processes happening simultaneously do need oxygen. One such process is the production of acetic acid, which can be pleasant in small amounts but leads to very sour, vinegar-like notes and "farmyard" aromas when concentrated. By fermenting coffee without oxygen, you can slow acetic acid production while encouraging more intense fruit flavours. This process can be carried out in various vessels, sometimes with added CO2 (carbonic maceration), and at different stages—either with whole fruit or after the coffee has been pulped.

The dry/natural process is the oldest and simplest method of preparing green coffee. Well-suited to environments with limited water access and hot climates, this process typically uses no water and requires no specialized equipment. After harvesting, coffee cherries are dried until they reach about 20% moisture content. They're then usually rested for a few weeks in bags before being sent to a mill for hulling and export preparation.

The cherries can be dried on large patios or raised African beds—large trays with a mesh base that allow increased airflow for even drying. Best practices include keeping the drying coffee in shade during the hottest parts of the day and avoiding re-wetting by rain or condensation. Regular turning and good ventilation are also crucial to prevent mould formation. To avoid defective seeds and sour fermentation off-flavours, it's best to sort the harvested cherries during the initial drying stage when under-ripe, over-ripe, and damaged cherries are easily spotted. After just a couple of days, the cherries turn a dark red-brown colour before becoming black, making it impossible to visually identify problem cherries.

Coffee begins fermenting from the moment it's picked and continues while there's enough moisture and high temperatures—conditions that favour microbial growth. This uncontrolled fermentation leads to the development of wild, fruity flavours and an increased perception of sweetness and body.